National Park Service

U.S. Department of the Interior

Natural Resource Stewardship and Science

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Rocky Intertidal Visitor Count at Cabrillo National Monument

Data Summary 2011

Natural Resource Data Series NPS/CABR/NRDS—2013/464

The following information below is an exerpt from this report. To read the report in its entirety, please go to the following link, or ask park staff to see a hard copy:

https://irma.nps.gov/DataStore/DownloadFile/467222

For report highlights continue reading:

Rocky Intertidal Visitor Count at Cabrillo National Monument

Data Summary 2011

Natural Resource Report NPS/CABR/NRDS—2013/464

Bonnie Phillips
National Park Service
Cabrillo National Monument
1800 Cabrillo Memorial Drive
San Diego, CA 92106

Dr. Tom Philippi
National Park Service
Cabrillo National Monument
1800 Cabrillo Memorial Drive
San Diego, CA 92106

Dr. Benjamin Pister
National Park Service
Cabrillo National Monument
1800 Cabrillo Memorial Drive
San Diego, CA 92106

April 2013

U.S. Department of the Interior

National Park Service
Natural Resource Stewardship and Science
Fort Collins, Colorado

Executive Summary

Due to the sensitive nature of the rocky intertidal marine habitat, it is essential to have an accurate assessment of the number of visitors to this area in order to make informed management decisions. Protection efforts to prevent the removal of marine life and habitat by visitors are in effect, however, negative human impacts go beyond the obvious threats. Damage can be done simply by people being present and walking on the algal turf and other organisms. These data are necessary to assess visitor capacity in the preservation of the rocky intertidal and also to ensure a positive visitor experience.

Visitor count data were collected near the rocky intertidal habitat at Cabrillo National Monument January 2011 through December 31, 2011. These data were collected using battery operated TrailMaster game counters on two separate trails in the coastal area of the park. The counters record an “event” every time an infrared beam is broken by visitors as they walk between the devices. A staff member downloaded the total number of events every two weeks and also replaced the batteries at the same time to ensure a continuous count. Calibration methods were used to increase accuracy in the overall method.

Between January 21, 2011 and December 31, 2011 total visitation for the rocky intertidal and coastal bluff area of the park is estimated at 214,000 visitors. This estimate is much higher than any previous estimates recorded for visitation in this section of the park. Prior to these data, the most recent method concluded an estimated count of 100,000 visitors per year in the rocky intertidal. It should be noted that these 2011 data include visitation on the coastal bluffs, whereas data from previous counting methods included only those visitors who were actually in the rocky intertidal.

These 2011 data show visitation was extremely high during the summer months, despite the lack of low-tides below 0.7 feet, which is considered the maximum tidal height for successfully viewing the intertidal life at Cabrillo National Monument. Visitation peaked in the afternoons on weekends and holidays, with some recorded visitation spikes during tides lower than 0.7 feet.   This indicates a small percentage of local visitors are aware of changing tide levels. Overall, these data show the majority of visitors do not seem to be aware of the existence of tide charts, nor are they aware of seasonal changes to daytime tide levels. These data also indicate the number of visitors entering the park before it opens and after it closes, but neither is of great concern to resource managers at this time.

These data will be used as a baseline and to assist in developing management strategies to ensure the preservation of Cabrillo’s intertidal resources for the enjoyment of this and future generations, as mandated by the National Park Service Mission.

Results

After the corrections were made, we estimated the number of total visitors for the rocky intertidal and coastal bluff area of Cabrillo National Monument for the calendar year 2011 was 213,714 visitors (Table 1). There were an estimated total of 86,863 visitors when the tide was less than 2.0 feet and 42,370 when the tide was less than 0.7 feet, which is optimal viewing for this park. The highest single day of visitation was Friday November 25, 2011 with 1,790 visitors. This was the day after Thanksgiving (Figure 4 and Table 2). There were a total of 525 visitors in the coastal area of the park prior to opening hours and 852 after closing hours in 2011. The total visitation for weekend days (Saturday & Sunday) was 94,681, or 956 people per day. The total number of visitors for combined weekdays (Monday through Friday) was 119,033, or 481 people per day (note, this number includes holidays falling on weekdays). The daily total visitor breakdown in Figure 4 shows the significant spike in visitation on weekends and holidays.

Table 1: Final 2011 total visitor count results after calibration and data correction. Total counts do not include 19 days of missing data (5.2%).

	2011 Total	Daily Average	Daily Max
Total Visitors	213713.7	617.7	1789.8
9am-5pm	211795.4	612.1	1785.9
Before Opening	525.1	1.5	29.6
After Closing	851.93	2.5	45.4
While Tide <0.7’	42369.5	279.7	1346.9
While Tide <2.0’	86863.1	311.3	1524.5
Weekdays	119032.9	481.9	1789.8
Weekend	94680.8	956.4	1558.7

For more information, including additional graphs, photographic documentation, tables of busiest days/months, tide chart comparison and discussion/conclusions by report authors, please read the full report by downloading it at the following link, or contact park staff:

https://irma.nps.gov/DataStore/DownloadFile/467222

Last revised 25-Apr-21